Adjustable biasing device for the keys of a business machine



Jan. 18, 1966 GRASHQFF 3,229,798

ADJUSTABLE BIASING DEVICE FOR THE KEYS OF A BUSINESS MACHINE Fil ed Feb. 26, 1965 INVENTOR. 7 11:5 8 Gran/w nieAde/ 57 gal-Ker ,uroRA/Ey United States Patent ADJUSTABLE BIASING DEVICE FOR THE KEYS OF A BUSENESS MACHINE Alfred Grasholf, Frankfurt am Main, Germany, assignmto Max Grundig, Furth, Bavaria, Germany Filed Feb. 26, 1963, Ser. No. 261,159 Claims priority, application Germany, Mar. 6, 1962, G 34,410 12 Claims. (Cl. 19717) The present invention relates to an adjustable biasing device, and more particularly to a device for resiliently biasing the keys of a business machine for the purpose of adjusting the force of the impact of type levers controlled by the key levers.

It is known to adjust the impact force of type lever action by adjusting the resilient resistance which has to be overcome by operator actuated keys. In a known construction, a spring serving this purpose is tensioned to different degrees by a turnable lever. In the known construction, the spring exerts a turning moment on the adjusting lever, so that the same has to be arrested in each adjusted position.

It is one object of the present invention to overcome this disadvantage of the prior art, and to provide an adjustable biasing device which can be tensioned to different degrees without requiring arresting means counteracting the spring force.

A related object of the present invention is to provide an adjustable biasing device having fewer parts than known constructions serving the same purpose, and being consequently easier to assemble, and less expensive.

Another object of the invention is to provide an adjustable biasing device of simple construction by which the resilient force acting on the key levers of a business machine is adjusted for the purpose of varying the resistance encountered by the fingers of an operator actuating the keys, which has an influence on the impact force exerted by the type levers on the platen.

With these objects in view, the present invention relates to an adjustable biasing device, which is advantageously applied to the keys of a business machine, such as a typewriter, One embodiment of the invention comprises a movable member, which may be used for biasing the keys of a typewriter, a turnable adjusting lever having a plurality of holding portions spaced different radial distances from its axis, and resilient means having one end secured to the movable member, and the other end thereof engaging a holding portion of the adjusting lever which is located on a line connecting the turning axis of the adjusting lever with a point of attachment of the resilient means to the movable member.

When the adjusting lever is turned between several adjusting positions, successive holding portions are located in the above-mentioned line and engaged by the resilient means. In all adjusted positions of the adjusting lever, the force exerted by the resilient means exerts no turning moment on the adjusting lever, and actually tends to hold the adjusting lever in the adjusted position selected and set by the operator.

Due to the fact that the holding portions are spaced different radial distances from the turning axis of the adjusting lever, the distance between the ends of the resilient means is varied in each adjusted position, resulting in a variation of the spring force acting on the movable member, and if this movable member is used for biasing a set of keys, all keys are diiferently biased by turning the adjusting lever. Such different bias will result in a different force required from the operator for actuating the keys, and consequently in a dilferent touch of the keys, and in an adjustment of the impact force exerted ice by the type levers. It is advantageous to use the movable member which biases the key levers, also for the purpose of raising the typewriter ribbon upon actuation of any selected key.

In the preferred embodiment of the invention, the end of the resilient means which engages the holding portions of the adjusting lever is provided with an engaging member guided in a guide slot extending in the direction of the above-mentioned line. The holding portions are formed as recesses in an opening in a head portion of the adjusting lever, and successively engaged by the engaging portion of the resilient means when the adjusting lever is turned. In this manner, the adjusting lever is arrested in each adjusted turned position.

The novel features which are considered as characteristic for the invention are set forth in particular in the appended claims. The invention itself, however, both as to its construction and its method of operation together with additional objects and advantages thereof, will be best understood from the following description of specific embodiments when read in connection with the accompanying drawing, in which:

FIG. 1 is a fragmentary perspective, and exploded view, partially broken off, and illustrating one embodiment of the invention; and

FIG. 2 is a fragmentary side view on an enlarged scale illustrating the adjustable biasing device of the invention.

Referring now to the drawings, the conventional features of a business machine or typewriter incorporating the present invention are not illustrated for the sake of clarity and simplicity, but the US. Patent 2,027,509 shows an inking ribbon actuating mechanism of such machines, which is moved by member 6 of the present invention. The supporting frame of the business machine includes a pair of vertical walls 1 and 2 on which a shaft 3 is mounted for turning movement. Shaft 3 has a pair of arms 4 and 5 connected by a rod 6. A spring 9 which will be described in greater detail hereinafter, biases member 3, 4, 5, 6 to turn in counterclockwise direction as viewed in the drawing, so that projections on arms 4 and 5 abut a stop rod 10 which is also secured to walls 1 and 2. A set of key levers 21, of which only one is shown in the drawing for the sake of simplicity, is provided. Each key lever is mounted for turning movement on a shaft 20, and has a key 25. A spring 22 biases each key lever 21 to turn in counterclockwise direction until abutting a stop 23 extending across all key levers 21.

When any selected key lever 21 is operated by depressing key 25, a projection 24 engages rod 6 of the movable member 3, 4, 5, 6 and turns the same in clockwise direction so that spring 9 is expanded and tensioned.

While each key lever 21 is biased by a spring 22, upon engagement of rod 6 by an actuated key lever 21, the spring force of spring 9 will be added to the force of the respective spring 22. Member 3, 4, 5, 6 is normally held by stop rod 10 in a position slightly spaced from projections 24 of key levers 21 in the inoperative position abutting stop rod 23, so that spring 9 becomes effective after key lever 21 has been operated to move away from stop rod 23.

The resilient means by which member 4, 5, 6 is biased is shown to be an elongated coil spring 9 having one end secured to an attaching means on arm 5. The attaching means is shown to be a bore 7 into which the end of this coil spring 9 is hooked. The other end of coil spring 9 is attached to the lower end of a connecting rod 8 which carries at its upper end a guide member in the form of a cylindrical stud 11 which passes through a guide slot 13 in wall 2.

On the other side of wall 2, a pivot means 14 is mounted, and supports an adjusting lever 15 for turning movement about an axis. As best seen in FIG. 2, a line connecting the axis of pivot means 14 with attaching bore 7 extends substantially perpendicularly to arm 5.

Adjusting lever 15 has a wider head portion formed with an opening which is bounded by a holding track including, for example, four recessed holding portions 16, 17, 18 and 19. Each holding portion 16, 17, 18 and 19 is spaced a different radial distance from the axis of pivot means 14, which is also the turning axis of adjusting lever 15.

A portion of guide member 11 projects from the other side of wall 2, and engages one of the recessed holding portions 16 to 19 of the adjusting lever. In the position illustrated in solid lines in FIG. 2, the engaging portion of guide member 12 engages the recessed holding portion 16 which is farthest spaced from the turning axis of adjusting lever 15, and from pivot means 14. When adjusting lever 15 is turned to the position illustrated in broken lines in FIG. 2, the engaging portion of member 11 will engage the recessed holding portion 18 which is closer to pivot means 14, so that spring 9 is stretched and its spring force increased. It will be understood that by manually turning adjusting lever 15 between four different adjusted positions, the tension of spring 9 can be adjusted so that a different spring force has to be overcome by each operated key lever 21.

In accordance with the present invention, the recessed holding portion engaged by engaging portion 11 is located on the line which connects the axis of adjusting lever 15 with the attaching means 7. Irrespective of the adjustment of the spring force by turning adjusting lever 15, the force of spring 9 will always act along the above mentioned line and directly on the pivot means 14. Consequently, the force of spring 9 will tend to hold adjusting lever 15 in each adjusted position, and there will be no turning moment exerted on lever 15 which would tend to turn adjusting lever 15 out of an adjusted position selected by the operator,

In constructions according to the known art, where the adjusted spring acted on the adjusting lever in a plane spaced from its axis, it was necessary to provide arresting means for the adjusting lever, and such arresting means had to sustain the turning moment exerted by the adjusted spring on the adjusting lever. Due to the fact that in accordance with the present invention no turning moment is exerted on the adjusting lever, no arresting means for the adjusting levers are required, and the adjusted spring 9 will tend to hold the adjusting lever in each adjusted position.

It is evident that the end of spring 9 could be directly connected to guide member 16 with the connecting rod 8 omitted. It is also possible to omit the guides slot 13, and to mount the adjusting lever on the same side of Wall 2' on which spring 9 is located, so that the end of spring 9 can be directly hooked into a recessed holding portion of the adjusting lever.

However, it is preferred to place pivot means 14, the operative holding portion 16 to 19, engaging member 11, spring 9, and attaching means 7 along a single line or plane extending substantially perpendicularly to the plane of arms 4- and 5.

When it is desired to adjust the device to a position in which the finger pressure to be exerted on keys 25 is lowest, adjusting lever 15 is manually turned to the position illustrated in solid lines in FIG. 2. In this position, spring 9 is permitted to contract to its shortest length, and consequently exerts the smallest biasing force on the key levers 21. Since no turning moment is exerted by spring 9, adjusting lever 15 is arrested in this position.

When a greater resilient resistance of the key levers is desired, adjusting lever 15 may be turned to the position illustrated in broken lines in FIG. 2 in which holding portion 18 is engaged by the engaging portion 11. Since holding portion 18 is spaced a shorter distance from the turning. axis of adjusting lever 15, spring 9 is stretched and exerts a greater resilient force so that the bias of the key levers 21 is increased. During such turning movement of adjusting lever 15, the slide portion of member 11 slides in slot 13 so that member 11 cannot be tran versely moved together with the turning adjusting lever 15. When adjusting lever 15 is turned in clockwise direction to its end position, spring 9 is fully expanded and the key levers are biased to require an even greater manual force for operation.

It will be understood that each of the elements described above or two or more together, may also find a useful application in other types of adjustable biasing devices differing from the types described above.

While the invention has been illustrated and described as embodied in a device for adjusting the bias of the keys of a business machine and thereby the finger pressure required for operation of the keys, it is not intended to be limited to the details shown, since various modifications and structural changes may be made without departing in any way from the spirit of the present invention.

Without further analysis the foregoing will so fully reveal the gist of the present invention'that others can by applying current knowledge readily adapt it for various applications without omitting features that, from the standpoint of prior art, fairly constitute essential characteristics of the generic or specific aspects of this invention and, therefore, such adaptations should and are intended to be comprehended within the meaning and range of equivalence of the following claims.

What is claimed and desired to be secured by Letters Patent is:

1. In a keyboard operated machine including a touch adjustment arrangement, in combination, a supporting frame: a plurality of key levers mounted pivotally and parallel to each other on said supporting frame; a movable elongated touch control member engaging all said key levers spaced from the points at which they are pivoted to said supporting frame; attaching means secured to said movable touch control member; an adjusting member mounted on said supporting frame for turning movement about. an axis, said adjusting member having a plurality of holding portions spaced different radial distances from said axis and being turnable about said axis into a plurality of adjusted positions in which different holding portions are located on a straight line connecting said axis with said attaching means; and tension spring means for pulling said movable elongated touch control member toward said adjusting member, said tension spring means having one end secured to said attaching means and the other end thereof engaging the holding portion which is located on said line, whereby in ditferent adjusted positions of said adjusting member the distance between the ends of said tension spring means and thereby the force of tension spring means pulling said movable elongated touch control member toward said adjusting means is varied while no turning moment is exerted on said adjusting member by said tension spring means.

2. Adjustable biasing device, comprising, in combination, supporting means; a movable member mounted on said supporting means and having an attaching means; an adjusting lever mounted on said supporting means for turning movement about an axis, said adjusting lever having a holding means including a plurality of holding portions spaced different radial distances from said axis, said adjusting lever being. turnable about said axis between a plurality of adjusted positions in which different holding portions are located on a straight line connecting said axis with said attaching means; a guide means extending along said straight line; resilient means having one end secured to said attaching means and having at the other end a guide member guided along said guide means and engaging the holding portion which is located on said line whereby in dilferent adjusted positions of said adjusting lever the distance between the ends of said resilient means and the resilient force acting on said movable member are varied while no turning moment is exerted on said adjusting lever by said resilient means.

3. Adjustable biasing device, comprising, in combination, supporting means; a movable member mounted on said supporting means and having an attaching means; an adjusting lever mounted on said supporting means for turning movement about an axis, said adjusting lever having a holding means including a plurality of holding portions spaced different radial distances from said axis, said adjusting lever being turnable about said axis between a plurality of adjusting positions in which different holding portions are located on a straight line connecting said axis with said attaching means; a stationary guide means having a guide slot extending along said straight line; resilient means having one end secured to said attaching means; and a guide member secured to the other end of said resilient means guided in said guide slot and engaging the holding portion which is located on said line whereby in different adjusted positions of said adjusting lever the distance between the ends of said resilient means and the resilient force acting on said movable member are varied while no turning moment is exerted on said adjusting lever by said resilient means.

4. Adjustable basing device for the keys of a business machine, comprising, in combination, supporting frame means; a plurality of key levers mounted on said supporting frame means; a member mounted on said supporting frame means for turning movement and including a part extending across said key levers and adapted to be engaged and turned by any operated key lever, said member having an attaching means; an adjusting lever mounted on said supporting frame means for manual turning movement about an axis, said adjusting lever having a holding means including a plurality of holding portions spaced different radial distances from said axis, said adjusting lever being manually turnable about said axis between a plurality of adjusted positions in which different holding portions are located on a straight line connecting said axis with said attaching means; and resilient means having one end secured to said attaching means and having at the other end thereof an engaging portion slidably engaging said holding means, said engaging portion abutting the holding portion which is located on said line whereby in different adjusting positions of said adjusting lever the distance between the ends of said resilient means, and the resilient force acting on said key levers are varied while no turning moment is exerted on said adjusting lever by said resilient means.

5. Adjustable biasing device for the keys of a business machine, comprising, in combination, supporting frame means having a guide means; a plurality of key levers mounted on said supporting frame means; a member mounted on said supporting frame means for turning movement and including a part extending across said key levers and adapted to be engaged and turned by any operated key lever, said member having an attaching means; an adjusting lever mounted on said supporting frame means for manual turning movement about an axis, said adjusting lever having a holding means including a plurality of holding portions spaced different radial distances from said axis, said adjusting lever being manually turnable about said axis between a plurality of adjusted positions in which different holding portions are located on a straight line connecting said axis with said attaching means and extending along said guide slot; an elongated spring having one end secured to said attaching means; and a guide member secured to the other end of said coil spring and being guided in said guide means, said guide member having an engaging portion projecting from said guide means slidably engaging said holding means, said engaging portion abutting the holding portion which is located on said line whereby in different adjusted positions of said adjusting lever the distance between the ends of said resilient means, and the resilient force acting on said key levers are varied while no turn- 6 ing movement is exerted on said adjusting lever by said resilient means.

6. Adjustable biasing device for the keys of a business machine, comprising, in combination, supporting frame means having a guide slot; a plurality of key levers mounted on said supporting frame means; a member mounted on said supporting frame means for turning movement and including a part extending across said key levers and adapted to be engaged and turned by any operated key lever, said member having an attaching means; an adjusting lever mounted on said supporting frame means for manual turning movement about an axis, said adjusting lever having a holding track including a plurality of recessed holding portions spaced different radial distances from said axis, said adjusting lever being manually turnable about said axis between a plurality of adjusted positions in which different recessed holding portions are located on a straight line connecting said axis with said attaching means and extending along said guide slot; an elongated coil spring having one end secured to said attaching means; and a guide member secured to the other end of said coil spring and being guided in said guide slot, said guide member having an engaging portion projecting from said guide slot slidably engaging said holding track, said engaging portion abutting the recessed holding portion which is located on said line whereby in different adjusted positions of said adjusting lever the distance between the ends of said resilient means, and the resilient force acting on said key levers are varied while no turning moment is exerted on said adjusting lever by said resilient means and said adjusting lever is arrested in the respective adjusted position.

7. Adjustable biasing device for the keys of a business machine, comprising, in combination, supporting frame means having a guide slot; a plurality of key levers mounted on said supporting frame means; a member mounted on said supporting frame means for turning movement and including a part extending across said key levers and adapted to be engaged and turned by any operated key lever, said member having an attaching means; an adjusting lever mounted on said supporting frame means for manual turning movement about an axis, said adjusting lever having a holding track including a plurality of recessed holding portions spaced different radial distances from said axis, said adjusting lever being manually turnable about said axis between a plurality of adjusted positions in which different recessed holding portions are located on a straight line connecting said axis with said attaching means and extending along said guide slot; an elongated coil spring having one end secured to said attaching means; and a connecting rod secured to the other end of said coil spring and having a guide portion guided in said guide slot and an engaging portion projecting from said guide slot slidably engaging said holding track, said engaging portion abutting the recessed holding portion which is located on said line whereby in different adjusted positions of said adjusting lever the distance between the ends of said resilient means, and the resilient force acting on said key levers are varied while no turning moment is exerted on said adjusting lever by said resilient means and said adjusting lever is arrested in the respective adjusted position.

8. Adjustable biasing device for the keys of a business machine, comprising, in combination, supporting frame means; a plurality of key levers mounted on said supporting frame means; a member mounted on said supporting frame means for turning movement and including a part extending across said key levers and adapted to be engaged and turned by any operated key lever, said member having an attaching means; pivot means mounted on said frame means; an adjusting lever mounted on said pivot means for manual turning movement about an axis, said adjusting lever having a head portion formed with an opening, said opening being bounded on one side by a holding track including at least three recessed holding portions spaced different radial distances from said axis, said adjusting lever being manually turnable about said axis between at least three adjusted positions in which recessed holding portions are located on a straight line connecting said axis and said pivot means with said attaching means; and resilient means having one end secured to said attaching means and having at the other end thereof an engaging portion slidably engaging said holding track, said engaging portion abutting the recessed holding portion which is located on said line whereby in different adjusted positions of said adjusting lever the distance between the ends of said resilient means, and the resilient force acting on said key levers are varied While no turning moment is exerted on said adjusting lever by said resilient means.

9. Adjustable biasing device for the keys of a business machine, comprising, in combination, supporting frame means; a plurality of key levers mounted on said supporting frame means; a member including a supporting shaft mounted for turning movement on said frame means, at least two arms projecting from said shaft, and a rod connecting said arms and extending across said key levers and adapted to be engaged by any operated key lever so that said member is turned thereby, one arm of said member having a bore; an adjusting lever mounted on said supporting frame means for manual turning movement about an axis, said adjusting lever having a holding means including a plurality of holding portions spaced different radial distances from said axis, said adjusting lever being manually turnable about said axis between a plurality of adjusted positions in which different holding portions are located on a straight line connecting said axis with said bore; and resilient means having one end secured to said bore and having at the other end thereof an engaging portion slidably engaging said holding means, said engaging portion abutting the holding portion which is located on said line whereby in different adjusted positions of said adjusting lever the distance between the ends of said resilient means, and the resilient force acting on said key levers are varied while no turning moment is exerted on said adjusting lever by saidvresilient means.

10. Adjustable biasing device for the keys of a business machine, comprising, in combination, supporting frame means having a guide slot; a plurality of key levers mounted on said supporting frame means; a member including a supporting shaft mounted for turning movement on said frame means, at least two arms projecting from said shaft, and a rod connecting said arms and extending across said key levers and adapted to be engaged by any operated key lever so that said member is turned thereby, said member being adaptedto be connected to means for raising the ribbon of the business machine for raising the ribbon when a key lever is operated, one arm of said member having a bore; an adjusting lever mounted on said supporting frame means for manual turning movement about an axis, said adjusting lever having a holding track including at least three recessed holding portions spaced different radial distances from said axis, said adjusting lever being manually turnable about said axis between at least three adjusted positions in which different recessed holding portions arev located on a straight line connecting said axis with said bore and extending along said guide slot; an elongated coil spring having one end movably secured to said bore; and a guide member secured to the other end of said coil spring and being guided in said guide slot, said guide member having an engaging portion projecting from said guide slot slidably engaging said holding track, said engaging portion abutting the recessed holding portion which is located on said line whereby in different adjusted positions of said adjusting lever the distance between the ends of said resilient means, and the resilient force acting on said key levers are varied while no turning moment is exerted on said adjusting lever by said resilient means and said adjusting lever is arrested in the respective adjusted position.

11.. A device as set forth in claim 10 wherein said frame means includes a wall formed with said guide slot and supporting said pivot means.

12. In a keyboard operated machine including a touch adjustment arrangement, in combination, a supporting frame; a plurality of key levers mounted pivotally and parallel to each other on said supporting frame; a movable elongated touch control member engaging all said key levers spaced from the points at which they are pivoted to said supporting frame; attaching means secured to said movable touch control member; an adjusting member mounted on said supporting frame for turning movement about an axis, said adjusting member having a holding track eccentric to said axis and including track portions spaced different radial distances from said axis, said adjusting member being turnable between a plurality of adjusted positions in which different track portions are located on a straight line connecting said axis with said attaching means; and tension spring means for pulling said movable elongated touch control member toward said adjusting member, said tension spring means having one end secured to said attaching means and the other end thereof engaging the track portion which is located on said straight line, whereby in different adjusted positions of said adjusting member the distance between the ends of said tension spring means and thereby the force of said tension spring means pulling said movable elongated touch control member toward said adjusting means is varied while no turning moment is exerted on said adjusting member by said tension spring means.

References (Iited by the Examiner UNITED STATES PATENTS 319,516 6/1885 Shank 24-270 X 1,418,149 5/1922 Hubble 24-69 1,876,138 9/1932 Fassett 2671 2,226,924 12/1940 Dobson 197-33 2,235,416 3/1941 Bridgwater 19733 2,344,167 3/1944 Pitman 19717 2,506,218 5/1950 Ingram 267-1 2,682,944 7/1954 Schremp -1 19733 2,987,161 6/1961 Rielander 197- 53 ROBERT E. PULFREY, Primary Examiner. 

1. IN A KEYBOARD OPERATED MACHINE INCLUDING A TOUCH ADJUSTMENT ARRANGEMENT, IN COMBINATION, A SUPPORTING FRAME: A PLURALITY OF KEYS LEVERS MOUNTED PIVOTALLY AND PARALLEL TO EACH OTHER ON SAID SUPPORTING FRAME; A MOVABLE ELONGATED TOUCH CONTROL MEMBER ENGAGING ALL SAID KEY LEVERS SPACED FROM THE POINTS AT WHICH THEY ARE PIVOTED TO SAID SUPPORTING FRAME; ATTACHING MEANS SECURED TO SAID MOVABLE TOUCH CONTROL MEMBER; AN ADJUSTING MEMBER MOUNTED ON SAID SUPPORTING FRAME FOR TURNING MOVEMENT ABOUT AN AXIS, SAID ADJUSTING MEMBER HAVING A PLURALITY OF HOLDING PORTIONS SPACED DIFFERENT RADIAL DISTANCES FROM SAID AXIS AND BEING TURNABLE ABOUT SAID AXIS INTO A PLURALITY OF ADJUSTED POSITIONS IN WHICH DIFFERENT HOLDING PORTIONS ARE LOCATED ON A STRAIGHT LINE CONNECTING SAID AXIS WITH SAID ATTACHING MEANS; AND TENSION SPRING MEANS FOR PULLING SAID MOVABLE ELONGATED TOUCH CONTROL MEMBER TOWARD SAID ADJUSTING MEMBER, SAID TENSION SPRING MEANS HAVING ONE END SECURED TO SAID ATTACHING MEANS AND THE OTHER END THEREOF ENGAGING THE HOLDING PORTION WHICH IS LOCATED ON SAID LINE, WHEREBY IN DIFFERENT ADJUSTED POSITIONS OF SAID ADJUSTING MEMBER THE DISTANCE BETWEEN THE ENDS OF SAID TENSION SPRING MEANS AND THEREBY THE FORCE OF TENSION SPRING MEANS PULLING SAID MOVABLE ELONGATED TOUCH CONTROL MEMBER TOWARD SAID ADJUSTING MEANS IS VARIED WHILE NO TURNING MOMENT IS EXERTED ON SAID ADJUSTING MEMBER BY SAID TENSION SPRING MEANS. 